From my experience I can say much that in my preps the lectures never helped me much at IMS......but the TEST SERIES rocked!! I feel in my opinion atleast that u can study at home easily if u have the right material at home without classes and all that but test series is what makes the difference....
If u r the guy who wants immense practice and feel that u r ready for tests early a good few months before CAT then u can take the TIME series coz they start early and have I think 30 Aimcats
If u're the guy who thinks he'll burn out (thats like me

) and thinks that 8 Simcats will do along with 8 Maxcats(which r okayish not really lik simcats)....then go for IMS......I went for the latter and I know how burnt out I was after 8 Simcats so I'd recommend this (just an opinion not advertising anythin out here).....and they have "awesome" variety all 8 of them they give u a feel of that "surprise" element which the CAT is notorious for
Having said that TIME DI sections are a class apart atleast difficulty wise so that should prepare u for almost anything in DI.......Maths aint bad either.....but the V.A was not as good (debatable hmm)
P.S: Finally whatever u do the CAT is gonna be different from any paper u ha got ure hands on before, but practice u have to right? so just mix and match the above options (Im in the dark abt CL, CF, etc papers) and keep givin them mocks! cheers! ATB